Kif1-binding protein (KBP/KIAA1279) binds to the motor domain of the KIF1B and KIF1C, and homozygous mutations of KBP cause Goldberg–Shprintzen syndrome, a severe disorder characterized by neurological symptoms, mental retardation, and disruption of white matter tracts. Here, KIFBP is linked to Goldberg-Shprintzen syndrome.